1. Field of the Invention
The present invention relates to a sensor that can detect a multiaxial force, and also to a manufacturing method of the sensor.
2. Description of Related Art
Japanese Patent Unexamined Publication No. 2005-31062 discloses a six-axis sensor including first and second disk-shaped members. Either of the first and second members has four diaphragms. The corresponding diaphragms of the first and second members are opposed to each other. A shaft stands at the center of each diaphragm. The shafts of each pair of opposed diaphragms of the first and second members are joined to each other with a bolt. The first and second members are thereby united. A number of strain gauges are disposed on the outer face of the first member. Forces and moments are detected on the basis of a change in the resistance value of each strain gauge.
A strain generation unit in which first and second disk-shaped members are interconnected through their shafts as described above is difficult to be formed by cutting a single body. In general, therefore, two or three parts are separately formed by cutting, and then the parts are interconnected by welding or with screws. However, in the first and second members, an annular groove must be formed around the shaft of each diaphragm. The size of each groove reduces as the sensor is miniaturized. This makes the cutting work of each groove difficult. It is particularly difficult to process each groove to be deep. It is very difficult to control variation in the thickness of the thin portion at each groove. Therefore, a special skilled worker or workers and much time are required for making such a strain generation unit. There is a problem that the miniaturization of the sensor leads to a marked increase in manufacturing cost.
The above problem may arise in not only a strain gauge type sensor as described above, but also a capacitance or resistance type sensor having a strain generation unit similar in shape.